Device and method relating to cable branching

ABSTRACT

The present invention relates to the field of arrangements at cable branchings and methods for manufacturing cable branches. One or more main conductors in the main cable are cut and released from the main cable. The cut and released main conductors are spliced with branch conductors extending from and end of a branch cable. A section of the main cable is arranged at a rail. A section of the branch cable, including the end, is also arranged at the rail. The tension reliever of the branch cable is fixed to the rail using a fixing device. A protective casing encloses the rail, the main cable section, the branch cable section, the spliced conductors and the fixing device.

The present invention relates to the fields of cable branching andmethods for the manufacturing of cable branches.

STATE OF THE ART

In some technical applications the need arises to branch main conductorsfrom one main cable to branch conductors in a branch cable.

Such a technical application is found in fibre optic access networks. Amulti-fibre cable (the main cable) must pass a number of boxes, socalled ONUs (Optical Network Unit) comprising circuitry forapproximately 30 subscribers. The ONUs transform the opticallytransmitted information from the multi-fibre cable to the electricallytransmitted (copper cable) information that reaches the subscribers.Thus, for each ONU a cable branch must be arranged. With such a cablebranch optical fibres (the main conductors) are branched from themulti-fibre cable to other optical fibres (the branch conductors) in asmaller optical cable (the branch cable) and the smaller optical cablethen runs up to the ONU. A maximum of approximately 16 ONUs may beconnected to one multi-fibre cable. To avoid high costs for digging whenthe cables are laid down, it is desirable to be able to determine onsite where the cable branches should be placed. Therefore, a reliableand simple form of cable branching, which can also be carried out underfield-like conditions is preferred. The alternative is to manufacturethe cable branches in a factory in advance, and it is of coursedifficult to know in advance where the cable branch is best placed, asone cannot know in advance the exact length of the main cable, thedigging conditions and the like.

When a cable branch is made, the main conductors to be branched must becut and in some way released from the main cable, so that they can bespliced with branch conductors belonging to a branch cable. The branchconductors to be spliced with the main conductors are in this situationnormally arranged so that they extend a distance from one end of thebranch cable, so that more space is achieved for performing the splice.Cable branches also normally comprise different kinds of protectionarrangements, against humidity, mechanical strain and the like.

The patent literature contains several examples of cable branches.

In the patent specification EP, A1, 0584600 an example of a cable branchis shown. Two portions, from which the casing has been removed, arearranged on the main cable. At the first of these portions from whichthe casing has been removed, the main conductors to be branched havebeen cut and then pulled out at the other portion from which the casinghas been removed, and have thus been released from the main cable. Thesemain conductors are spliced with branch conductors extending from theends of, in this case, two branch conductors. The splices are placed inmechanical protection arrangements. The ends of the cable casing on bothsides of the other portion from which the casing has been removed aremechanically connected by means of a beam, and the ends of the twobranch conductors are also mechanically connected to the beam. A housingis arranged around the second portion from which the casing has beenremoved, the beam, the spliced conductors and the branch cable ends. Theends on both sides of the first portion from which the casing has beenremoved have been connected to a beam and a housing has been arrangedalso around this portion from which the casing has been removed.

This cable branching has disadvantages. Double sets of beams andhousings are needed and therefore also double work. The housing must bemanufactured specially and each housing only fits cables of a specificsize.

In the patent specification DE, A1, 363 an example of a cable branch isshown. A portion from which the casing has been removed is arranged atthe main cable. The portion from which the casing has been removed isarranged in a stretched-out state in a housing. The main conductors havebeen cut at the portion from which the casing has been removed and thuseven been released from the main cable. The cut main conductors havebeen spliced with branch conductors extending from the end of a branchcable. The branch cable end is fastened to the housing. The splices arearranged in a mechanical protector.

This cable branching has disadvantages. If a length of cable which isfeasible to work with is desired when performing the splice, the portionfrom which the casing has been removed must be quite long, which resultsin a big housing. The housing must be manufactured specially and onlyfits cables of a specific size.

In the patent specification DE, A1, 363 another example of a cablebranch is also shown. A portion from which the casing has been removedis arranged at the main cable, and a circular cut is made through thecable casing, at a distance from the portion from which the casing hasbeen removed. In this way a movable piece of the casing is arrangedbetween the portion from which the casing has been removed and thecircular cut. If the movable piece of casing is moved in the directiontowards the portion from which the casing has been removed an openingappears at the circular cut. In this opening the main conductors to bebranched are cut. The movable piece of casing is moved back and the mainconductors to be branched are pulled out at the portion from which thecasing has been removed, so that the main conductors to be branched arereleased from the main cable. The cut main conductors are spliced tobranch conductors extending from the end of a branch cable. The splicesare placed in a mechanical protector. The portion from which the casinghas been removed is placed in a stretched-out state in a housing andanother housing is arranged around the circular cut.

This cable branching has disadvantages. Two housings are required, andthus double work. The housings must be manufactured specially and eachhousing only fits a specific cable size.

SUMMARY OF THE INVENTION

The object of the present invention is to solve the following problems:firstly to achieve a cable branch where a number of main conductors in amain cable are branched to a number of branch conductors in a branchcable; secondly to ensure that the cable branching is easy to performand requires few complicated or specially manufactured parts and thirdlyto ensure that the cable branching can easily be carried out underfield-like conditions.

The problems stated above are generally solved as follows: A piece ofthe main cable is mounted on a rail, the purpose of which is tomechanically relieve and provide a certain amount of protection to thecable branch. The ends of a number of branch conductors which have beenarranged so that they extend a distance past one end of a branch cable,are spliced to the ends of a number of main conductors which have beencut and released from the main cable. One portion of the branch cable,comprising the end of the branch cable, is mounted on the rail. In thecase when the branch cable comprises a tension reliefin part it issuggested according to the invention that the tension reliefing part befixed at the rail by means of a fixing device, for example a lockingscrew. According to the invention it is also proposed that the fixingdevice may be moved along the rail, thus providing possibility ofredoing the splice between the main conductors and the branchconductors--if the splice should have failed in any way--since thebranch cable may then be moved far enough to provide sufficient slack inthe spliced conductors for the old splices to be removable so that newones may be made. Finally a tight-fitting protective casing is mountedaround the rail, the spliced conductors and the portions of the maincable and the branch cable which have been mounted at the rail.

More concretely, the above stated problems are solved as follows: Therail in this situation is comprised of an elongated metal plate, whichhas been bent so that two edges have been formed on the upper side ofthe plate. The cable casing is removed along a portion of the cable anda circular cut is made in the cable casing. In this way a movableportion of the cable casing is created, which may be moved back andforth between the place where the circular cut through the cable casingwas made and the portion from which the casing has been removed. Bymoving the movable portion of the cable casing towards the portion fromwhich the casing has been removed a small opening occurs at the placewhere the circular cut through cable casing was made. In the opening themain conductors to be branched are identified and cut. The cut mainconductors are pulled out at the portion from which the casing has beenremoved, and the movable portion of the cable casing is moved backtowards the place where the circular cut was made through the cablecasing. This frees the main conductors from the main cable and they arespliced with the branch conductors of the branch cable. The portion ofthe main cable to be mounted at the rail is arranged so that it liesclose against the plate and one of the edges. The main cable is fixed tothe rail by means of fixing means, for example lockable metal strips.The portion of the branch cable to be mounted on the rail is arranged sothat is lies close against the plate and the other edge. The branchcable is fixed to the rail by means of fixing means in a similar way asthe main cable. According to the invention it is proposed to arrange theprotective casing according to the following. A wrapping which isrelatively stable in shape is mounted around the rail, the cableportions mounted on the rail and the spliced conductors. The outside ofthe wrapping is preferably smooth. Adhesive tape is then wound aroundthe wrapping with the adhesive side out. A watertight cloth is arrangedaround the tape-wound wrapping. The cloth may for example be made fromself-vulcanizing rubber cloth. Around the cloth, adhesive tape is wound;this time with the adhesive side turned inwards.

In addition to solving the problems stated above, the invention has thefollowing advantages. Firstly it provides a cable branch which may bemade at a relatively low cost. Secondly, exactly the same parts may beused for branching cables of somewhat varying size.

The invention will now be described in more detail by means of preferredembodiments and with reference to the enclosed drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a perspective view of a cable branch according to theinvention.

FIG. 1b a perspective view of a detail of a cable branch according tothe invention.

FIG. 2a is a cross-section of a cable branch according to the invention.

FIG. 2b is a cross-section of a cable branch according to the invention.

FIG. 2c is a cross-section of a cable branch according to the invention.

FIG. 2d is a cross-section of a cable branch according to the invention.

FIG. 3 is a cross-section of a cable branch according to the invention.

FIG. 4 is a flow chart of a method for making a cable branch accordingto the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

In FIG. 1a it is shown how a possible cable branch according to theinvention looks before the protective casing 117, 95 shown in FIG. 3 hasbeen mounted around the cable branch.

A portion 3 from which the casing has been removed is arranged in a maincable 1, and at a distance form the portion from which the casing hasbeen removed a circular cut 5 is also made in the cable casing. Theportion 7 of the cable casing between the portion 3 from which thecasing has been removed and the circular cut 5 thus is movable along thecable 1. If the movable portion 7 is moved in the direction towards theportion 3 from which the casing has been removed an opening occurs atthe point where the circular cut 5 was made. In this opening the mainconductors 41-44 to be branched have been identified and cut. After themain conductors were cut, the movable portion 7 was moved back, so thatthe opening was closed. The cut main conductors 41-44 have then beenpulled out at the portion 3 from which the casing was removed and inthis way the main conductor ends to be spliced with branch conductors53-56 in a branch cable 2 are released from the main cable.

In FIG. 1a a section of the main cable is arranged on a rail 19. Thismain cable section extends substantially lengthwise to the rail andcomprises both the portion 3 from which the casing has been removed andthe circular cut 5. The main cable section is fixed to the rail by anumber of fixing means 9-17 which in the embodiment of the inventionshown in FIG. 1a consist of lockable metal strips 9-17. In FIG. 1a themain cable section is fixed with nine metal strips 9-17, but it is ofcourse not necessary to use this exact number. It is however feasible toplace one or a few metal strips at both ends of the rail. It may also befeasible to place one or a few metal strips at the movable portion ofthe cable casing.

The rail 19 which is shown on its own in FIG. 1b is in the embodimentshown made from an elongated rectangular plate 21. The plate has beenbent so that a first 23 and a second 25 edge have been formed on theupper side of the plate, and these edges 23 and 25 extend in thelongitudinal direction of the rail 19. Through recesses 27-38 and 115are arranged in the plate 21, between the edges 23 and 25.

The cut main conductors 41-44 in FIG. 1a have been spliced with branchconductors 53-56 which extend from the end 63 of a branch cable 2. Inthe embodiment shown in FIG. 1a the conductors 41-44 and 53-56 areoptical fibres. The splicing of optical fibres often takes place withfilsing, which is a method well known to the person skilled in the art,and the fused joints are normally enclosed in mechanical protectors 47and 49, so called splice protection sleeves. Such splice protectionsleeves are commercially available and a known manufacturer is RaychemCorporation. In FIG. 1a the fused joints have been placed in two spliceprotection slesves 47 and 49 and the splice protection sleeves are fixedto the rail by means of a spring clip 51.

In FIG. 1a a section of the branch cable 2 is arranged to lie close tothe plate 21 and the second edge 25. This branch cable section comprisesa branch cable end 63 and is fixed to the rail by means of fixing means65 and 66 which in the shown embodiment consist of lockable metal strips65 and 66 which in the exemplary embodiment comprise lockable metalstrips.

The branch conductors 53-56 comprised in the branch cable, which havebeen spliced with the cut main conductors 41-44 have not been cut at thebranch cable end 63, but extend a distance from the branch cable end.This distance has been chosen so that fibre lengths which are feasibleto work with during fusing are obtained. The branch cable 2 in FIG. 1acomprises a centrally located tension relief means 61. The tensionrelief means 61 is not cut at the branch cable end 63 but extends adistance from the branch cable end. This extending portion of thetension relief means 61 is fixed to the rail 19 by means of a fixingdevice 59, which in one exemplary embodiment is comprised of a lockingscrew arrangement.

In FIG. 2(a-d) four cross-sections of the cable branching in FIG. 1a areshown.

FIG. 2a shows the cross-section labelled A in FIG. 1a. Here the maincable 1 can be seen in cross-section. The main cable 1 in the embodimentshown here is a slotted core cable. Within the cable casing 69 there isa core 71--normally manufactured in a plastic material--in which sixgrooves 73 are arranged in the longitudinal direction of the cable 1. Ineach groove 73 there are two so called ribs 77 and 75 which in turncomprise four optical fibres 78 each. The ribs 77 and 75 and the opticalfibres are colour marked in such a way that an identification of thesingle fibres is possible. The main cable 1 in the figure also comprisesa centrally located tension reliever 79.

FIG. 2a also shows in detail how one of the metal strips 10 is arrangedto fix the main cable 1 to the rail 19. The metal strip 10 here firstruns on the lower side of the plate 21 and then around the first edge 23and part of the circumference of the cable, to finally return throughone of the recesses 28 to the lower side, where the metal strip 10 islocked with a locking arrangement 81. The metal strip 10 in this wayforms a loop surrounding the main cable 1 and keeps this lying close tothe rail 19. Lockable metal strips are commercially available, forexample Panduit MLT 2S/CP or the like.

FIG. 2b shows the cross-section labelled B in FIG. 1a. The figure showshow the two splice protection sleeves 47 and 49 are fixed to the rail 19by a spring clip 51 which in the figure is made up of a bent metal strip51. The metal strip 51 is fixed in one of the recesses 38 and runs firston the lower side of the plate 21 and then around the second edge 25, tofinally lie close to the upper sides of the splice protection sleeves 47and 49 and in this way press the splice protection sleeves against theupper side of the plate. Where the metal plate 51 lies close against thesplice protection sleeves 47 and 49, it has been given a somewhat bentshape, so that it firmly grasps the splice protection sleeves.

FIG. 2c shows the cross-section labelled a D in FIG. 1a. Here the branchcable 2 can be seen in cross-section. The branch cable 2 is also, in theembodiment shown here, a slotted core cable. The branch cable 2 in FIG.2c comprises inside its cable plate 91 a core 93 with three grooves 95.In each groove four optical fibres run. The branch cable 2 lies incontact with the plate 21 and the second edge 25 and is fixed to therail 19 in a similar way as the main cable 1, by means of two fixingelements 65 and 66 in the form of lockable metal strips 65 and 66. Inthe figure the tension reliever 61 centrally located in the branch cable2 can be seen.

FIG. 2d shows the cross-section labelled C in FIG. 1a. The way in whichthe tension reliever 61 of the branch cable 2 is fixed to the rail 19 isshown in detail in this Figure.

The tension reliever 61 is here fixed with a locking screw arrangement59 comprising a screw 99, a washer 111 and a nut 113.

The screw comprises a first 101 and a second 103 end. Threads arearranged at the first 101 end of the screw and these extend a certaindistance along the screw 99. A through hole 105, of circularcross-section, is arranged in the screw 99 at the second end 103 of thescrew. The hole 105 is arranged in such a way that the hole penetratesthe screw 99 substantially transverse to the longitudinal direction ofthe screw. At the second end 103 of the screw 99 an extended portion 107is also arranged, in such a way that the longitudinal direction of theextending portion is substantially transverse to the longitudinaldirection of the screw. The extending portion 107 comprises a groove109, of semicircular cross-section, extending in the longitudinaldirection of the extending portion. The groove 109 is here arranged sothat the half of the wall of the hole extending through the screw 99located farthest from the first end 101 of the screw is comprised by apart of the extension of the groove.

The washer 111 is a metal washer 111 with a circular through hole, thediameter of this hole exceeding the diameter of the screw 99.

The nut 113 is a hexagonal nut, which fits the threads of the screw 99.

The locking screw arrangement 59 fixes the tension reliever 61 of thebranch cable 2 according to the following. The washer 111 lies closeagainst the upper side of the plate 21 in such a way that the hole inthe washer is aligned with one of the holes 115 in the plate. This hole115 is hidden by the second edge 25 in FIGS. 1a and 1b, but is shown inFIG. 2d. The tension reliever 61 in the branch cable 2 is slippedthrough the. hole l05 in the screw 99, and the screw passes through thehole in the washer 111 and continues through the hole 115 so that itsfirst end 101 comes out on the lower side of the plate 21. The nut 113is screwed onto the screw 99 on the lower side of the plate 21. Thescrew 99 is arranged so that the longitudinal direction of the extendingportion 107 substantially coincides with the longitudinal direction ofthe rail 19. The tension reliever 61 is squeezed between the groove 109in the extending portion 107 and the washer 111 and when the nut istightened the tension reliever is therefore fixed to the locking screwarrangement. The rail is squeezed between the nut 113 and the washer 111and when the nut 113 is tightened the locking screw arrangement 59 istherefore fixed to the rail 19, whereby the tension reliever 61 will ofcourse also be fixed to the rail.

The recess 115 through which the screw 99 goes, extends in thelongitudinal direction of the rail. If the nut 113 is loosened, thelocking screw arrangement 59 can therefore be moved in the longitudinaldirection of the rail 19. This is advantageous if the splices betweenthe conductors 41-44 and 53-56 have failed in any way, as the lockingscrew arrangement 59 and the branch cable 2 may then be moved a bitforward so that enough slack is obtained in the spliced conductors tomake it possible to remove the failed splices and make new ones.

Until now the cable branch has been shown without the protective casing117 which according to the invention is suitably included in the cablebranch. Of course a cable branch according to the invention may be usedalso without a protective casing--if for some reason it should beconsidered unnecessary to have one. In FIG. 3 a cross-section of thecable branch is shown in which the protective casing 117 is included.The position of the cross section corresponds approximately to theposition of the cross section labelled D in FIG. 1a.

The protective casing 117 comprises a wrapping 119 which is relativelystable in shape, arranged so that it encloses the rail 19, the maincable section, the branch cable section, the spliced conductors 41-44and 53-56 and the locking screw arrangement 59. The wrapping 119 has acylindrical, prismatic or other similar elongated shape, and thelongitudinal direction of this shape substantially coincides with thelongitudinal direction of the rail 19. In the embodiment shown in thefigure the shape is substantially prismatic. The side of the wrappingfacing outwards as a suggestion is smooth. In the embodiment shown inFIG. 3 the wrapping 119 is made of a folded sheet of paper and thesmooth side is made up of an aluminium film arranged on the paper sheet.Paper sheets of this kind are commercially available, for example of thekind Nitto NTS or the like. Adhesive tape 121 is arranged around thewrapping 119 and the adhesive tape here is arranged with the adhesiveside facing way from the wrapping.

The tape-wound wrapping 119 is enclosed in a watertight cloth 123. Inthe embodiment shown in FIG. 3 the cloth is made up of aself-vulcanizing rubber cloth 123. Such rubber cloths are commerciallyavailable, for example of the kind Nitto G057 or the like. Around thecloth adhesive tape 125 is arranged, this time with the adhesive sidefacing the cloth.

The method of manufacturing a cable branch according to the invention issimple and precise and will be described here, with reference to theflow chart in FIG. 4.

The method starts 129 with the main cable 1 being prepared. A portion 3from which the casing has been removed is arranged in the main cable 1.The length of the portion 3 from which the casing has been removed issuitably between five and fifteen centimetres long. A circular cut 5 isarranged in the cable casing 69, whereby a movable piece 7 of the casingis formed between the circular cut and the portion 3 from which thecasing has been removed. The distance between the portion 3 from whichthe casing has been removed and the circular cut 5 is suitably between50 and 90 centimeters. The movable piece 7 of casing is moved in thedirection towards the portion 3 from which the casing has been removed,so that an opening is formed at the place where the circular cut 5 wasmade. In the opening the main conductors 41-44 to be branched areidentified and cut. The movable piece 7 of casing is moved back so thatthe opening is closed, and the main conductors 41-44 to be branched areidentified and pulled out at the portion from which the casing has beenremoved.

The method continues 131 with the main cable 1 being mounted on the rail19. The main cable 1 is placed so that it lies close against the plate21 and the first edge 23 and fixed with the metal strips 9-17. The maincable 1 in this step is laid so that the portion 3 from which the casinghas been removed and the circular cut 5 are located between the firstand the second end of the rail 19. The main cable 1 should preferably beplaced so that the main conductors 41-44 to be branched aresubstantially located on the same level as the rail 19.

The method continues 133 with the branch cable 2 being prepared. Thebranch cable 2 is cut so that a branch cable end 63 is formed. Thebranch conductors 53-56 to be spliced with the main conductors 41-44 tobe branched and the centrally located tension reliever 61 of the branchcable 2 are however not cut at the end 63 of the branch cable but arearranged so that they extend suitable distances from the branch cableend.

The method continues 135 with the splice being made. The conductors tobe spliced--that is the main conductors 41-44 to be branched and thebranch conductors 53-56 extending from the branch cable end 63--arecut--if necessary, to suitable lengths. The conductors 41-44 and 53-56are spliced and the mechanical protectors 47 and 49 (the spliceprotection sleeves) are applied around the joints.

The method continues 137 with the branch cable being mounted. A sectionof the branch cable, comprising the branch cable end 63, is arranged atthe rail 19 so that it lies close to the plate 21 and the second edge25. It is hereby ensured that the spliced conductors 41-44 and 53-56 arestretched to a suitable extent. The branch cable 2 is locked to the rail19 with at least two metal strips 65 and 66, and the mechanicalprotection arrangements 47 and 49 are fixed to the rail 19 by means ofthe spring clip 51. The tension reliever 61 of the branch cable 2 isfixed to the rail by means of the locking screw arrangement 59.

The method is ended 139 with the protective casing being mounted. Thewrapping 119 is folded around the rail 19, the cable sections arrangedat the rail, the spliced conductors 41-44 and 53-56 and the lockingscrew arrangement 59 in such a way that it is given a cylindrical,prismatic or other similar elongated shape, whereby the longitudinaldirection of this shape is made to substantially coincide with thelongitudinal direction of the rail. Adhesive tape 121 is wound from themiddle of the wrapping 119 to one end of the wrapping. Then the adhesivetape 121 is wound to the other end and back to the middle, whereby twolayers of adhesive tape are arranged around the wrapping 119. In thisprocedure the adhesive tape 121 is wound with the adhesive side facingaway from the wrapping 119, to facilitate a possible reopening of thesplices. The self-vulcanizing rubber cloth 123 is wound once around thetape-wound wrapping 119. Finally two layers of adhesive tape 125 arewound around the cloth 123 in a similar way as around the wrapping 119,but this time with the adhesive side facing the cloth.

In the above, the main conductors in the main cable have been branchedto one branch cable. Of course it is possible to branch the mainconductors to branch conductors belonging to several different branchcables. These branch cables may then be prepared and mounted on the railin a similar way as the branch cable in the embodiments described above.

What is claimed is:
 1. A cable branching system comprising a main cable,in turn comprising at least one main conductor, at least one branchcable, in turn comprising a branch cable end (63) and at least onebranch conductor and at least one splice, arranged to splice the end ofthe at least one branch conductor extending from the branch cable end,wherein the cable branching comprises a substantially stretch and bendresistant rail, in turn comprising a first and a second end, that asection of the main cable substantially coincides with the longitudinaldirection of the rail, that a branch cable section, including the branchcable end, is arranged on the rail, whereby the longitudinal directionof the branch cable section substantially coincides with thelongitudinal direction of the rail, and that a protective casing isarranged to enclose the rail, the main cable section, the branch cablesection and the spliced conductors.
 2. The cable branching systemaccording to claim 1, wherein the main cable comprises a cable casingwhereby the at least one main conductors are arranged inside the cablecasing, that a portion from which the casing has been removed isarranged in the main cable, that a circular cut is made in the cablecasing has been removed and the circular cut, and that the cut mainconductors have been cut at the circular cut and pulled out at theportion from which the casing has been removed.
 3. The cable branchingsystem according to claim 2, wherein the branch cable end faces theportion from which the casing has been removed, that the branch cableend is positioned between the portion from which the casing has beenremoved and one predetermined end of the two ends of the rail, and thatthe circular cut is arranged closer to the predetermined end than theportion from which the casing has been removed.
 4. The cable branchingsystem according to claim 2, wherein the protective casing comprises arelatively shape-stable wrapping, arranged to enclose the rail, the maincable section, the branch cable section and the spliced conductors, thatthe wrapping is arranged to assume a substantially cylindrical shape,whereby the longitudinal direction of the cylindrical shapesubstantially coincides with the longitudinal direction of the rail,that the side of the wrapping facing out is smooth, that at least onelayer of adhesive tape is arranged around the wrapping, whereby the tapeis arranged with the adhesive side away from the wrapping, that theprotective casing comprises a watertight cloth arranged to tightlyenclose the tape-wound wrapping, and that at least one layer of adhesivetape is arranged around the cloth, whereby this adhesive tape isarranged with the adhesive side facing the cloth.
 5. The cable branchingsystem according to claim 4, wherein the wrapping is made up of a papersheet, whereby the smooth side of the wrapping facing out is made up ofan aluminum film arranged on the paper sheet.
 6. The cable branchingsystem according to claim 4, wherein the cloth is made up of aself-vulcanizing rubber cloth.
 7. The cable branching system accordingto claim 1 wherein the rail comprises an elongated plate, that the platecomprises a first and a second edge arranged on one side of the plate,whereby the edges extend substantially in the longitudinal direction ofthe rail, that the main cable section and the branch cable section arearranged between the first edge and the second edge, that the main cablesection is arranged to lie in contact with both the plate and the firstedge, that the branch cable section is arranged to lie in contact withthe plate and the second edge.
 8. The cable branching system accordingto claim 7, wherein the main cable section is arranged on the rail bymeans of lockable strips, that at least one lockable strip is arrangedsubstantially at the first end of the rail and that at least onelockable strip is arranged substantially at the other end of the rail.9. The cable branching system according to claim 7, wherein the branchcable section is arranged at the rail by means of at least two lockablestrips.
 10. The cable branching system according to claim 1, wherein thebranch cable comprises a tension relieving part (61), that the cablebranching comprises a fixing arrangement (59), arranged to fix thetension relieving part to the rail, and that the protective casing isarranged to enclose the fixing arrangement too.
 11. The cable branchingsystem according to claim 10, wherein the fixing arrangement is movablein the longitudinal direction of the rail.
 12. The cable according toclaim 1 wherein at least one mechanical protection device is arranged toprotect at least one of the splices, and that at least one spring clipis arranged to fix the mechanical protection devices to the rail.
 13. Amethod for manufacturing a cable branching, wherein cutting at least onemain conductor and releasing it from a main cable (1), arranging a maincable section at a stretch and bend resistant rail (19) comprising afirst and a second end, in such a way that the longitudinal direction ofthe main cable section is made to substantially coincide with thelongitudinal direction of the rail, arranging branch cable end at abranch cable whereby at least one branch conductor is arranged to extenda predetermined distance from the branch cable end, arranging at lestone splice as to splice one of the at least one branch conductorsextending from the branch cable end, and arranging a branch cablesection comprising the branch cable end at the rail in such a way thatthe longitudinal direction of the branch cable section is made tosubstantially coincide with the longitudinal direction of the rail. 14.The method according to claim 13, wherein arranging a protective casingto enclose the rail, the main cable section, the branch cable sectionand the spliced conductors.
 15. A cable branching system comprising:amain cable having at least one main conductor; at least one branchcable, having at least one branch conductor, which communicates with themain cable; a rail which supports the main cable section and the atleast one branch cable in the longitudinal direction; and a protectivecasing arranged to enclose the rail, the main cable and the at least onebranch cable.
 16. The cable branching system of claim 15, wherein the atleast one branch cable includes at least one splice.
 17. The cablebranching system of claim 15, wherein the main cable comprises a cablecasing whereby the at least one main conductors are arranged inside thecable casing, the cable casing has a removed portion and remainingportion, wherein the remaining portion is able to move along thelongitudinal direction due to a circular cut in the cable casing. 18.The cable branching system of claim 15, further including at least onelockable strip.
 19. The cable branching system of claim 15, wherein theat least one lockable strip encloses the rail.